package network;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class TcpEchoServer {
    private ServerSocket serverSocket = null;   // 外场销售

    public TcpEchoServer(int port) throws IOException {
        serverSocket = new ServerSocket(port);
    }

    public void start() throws IOException {
        ExecutorService executorService = Executors.newCachedThreadPool();
        System.out.println("服务器启动！");
        while (true) {
            Socket clientSocket = serverSocket.accept();   // 内场销售好多个
            // 如果直接调用，该方法会导致这个循环的二次执行，导致accept不及时
            // 创建新的线程，用新线程调用 processConnection
            // 每次来一个新的客户端都搞一个新的的线程即可！
//            Thread t = new Thread(()->{
//                try {
//                    processConnection(clientSocket);
//                } catch (IOException e) {
//                    e.printStackTrace();
//                }
//            });
            executorService.submit(new Runnable() {
                @Override
                public void run() {
                    try {
                        processConnection(clientSocket);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            });
        }
    }

    // 通过这个方法来处理一个连接
    // 读取请求
    // 根据请求计算相应
    // 把响应返回给客户端
    private void processConnection(Socket clientSocket) throws IOException {
        System.out.printf("[%s:%d] 客户端上线！\n",clientSocket.getInetAddress().toString(),
                clientSocket.getPort());
        // try() 这种写法, ()中允许写多个流对象。 使用 ; 来分割
        try (InputStream inputStream = clientSocket.getInputStream();
             OutputStream outputStream = clientSocket.getOutputStream()) {
            Scanner scanner = new Scanner(inputStream); // 字符流
            PrintWriter printWriter = new PrintWriter(outputStream);
            while (true) {
                // 1，读取请求
                if (!scanner.hasNext()){
                    // 读取的流到结尾（对端关闭了）
                    System.out.printf("[%s:%d] 客户端下线！\n",clientSocket.getInetAddress().toString(),
                            clientSocket.getPort());
                    break;
                }
                // 直接使用 scanner 读取一段字符串
                String request = scanner.next();
                // 2. 根据请求计算相应
                String response = process(request);
                // 3. 把相应返回客户端
                printWriter.println(response);
                printWriter.flush();
                System.out.printf("[%s:%d] req: %s; resq: %s\n", clientSocket.getInetAddress().toString(),
                        clientSocket.getPort(),request,response);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            clientSocket.close();
        }
    }

    private String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        TcpEchoServer tcpEchoServer = new TcpEchoServer(9090);
        tcpEchoServer.start();
    }
}
